Transmissible Spongiform Encephalopathies (TSEs) are neurological diseases that have been found in humans, cattle, sheep and other mammals (e.g. cats, goats, deer, antelope). The agent of disease is believed to be an abnormal prion protein (or is prion associated). An abnormal prion is a protein with an abnormal folding structure when compared to the naturally occurring prion found in nervous and lymphoreticular tissues. Various abbreviations are in use to refer to this: Prion Protein (PrP); Abnormal Prion Protein (PrPab); Resistant Prion Protein (PrPres); Scrapie Prion Protein (PrPsc) and others. In most instances the abnormal prion is resistant to protein kinase digestion, a feature used in diagnostic techniques. Clinical signs include progressive ataxia and pruritis. Histology (immunohistochemistry) usually shows vacuolation and an accumulation of prion proteins in various parts of the CNS (especially the brain and spinal cord).